The invention is directed to improved apparatus for actuating the throttle valve of an internal combustion engine. A known apparatus of this type includes a hydraulic cylinder disposed in the course of the linkage between the gas pedal and throttle valve, or other components with which the power output by an internal combustion engine can be varied. In the normal situation, this hydraulic cylinder is moved along with the throttle valve actuation, and it enables a deviation or difference in travel between the adjusting movement at the gas pedal and the adjustment of the throttle valve as a result of the fact that selectively, either the hydraulic cylinder is acted upon with suitable pressure of a pressure medium, or pressure is bled off (such as shown in German Offenlegungsschrift 33 23 561; and U.S. Pat. 4,415,347). Such hydraulic cylinders are typically also provided in systems having anti-skid or anti-lock brake systems (ABS), and they result from an expansion of the basic functions of such systems, in which suitable brake force modulations are performed, by action on the wheel brake cylinders or systems preceding them, not only whenever the wheels of the vehicle lock during braking but also whenever the wheels threaten to spin during acceleration, for example in fast starts as well as in normal starts on a slippery surface. The signals provided by the existing wheel sensors can then also be utilized for this kind of drive slip regulation (ASR), in which case signals from the brake pedal and driving pedal (gas pedal) should also be taken into account.
ASR control is possible not only by exerting a braking action upon spinning wheels, but also by reducing the engine power output, or in other words by retracting the throttle valve position, thereby lessening the tendency of the driven wheels to spin, regardless of the intention of the driver and regardless of the actual position of the driving pedal.
Such pressure-dependent hydraulic cylinders, which are primarily moved along with the linkage, can be complicated and difficult to incorporate in the connecting linkage between the gas pedal and the throttle valve actuation means, because at least one pressure connection must be present in any case, and furthermore, a reverse actuation course through the switching systems, or in other words accelerating variably hard, is not possible in certain cases, such as when the gas pedal is in the idling position.